Definitely see that counselor, it will help a lot.
I'm reading a really great book called "Masterminds and Wingmen," which is about the development and socialization of boys. It's from the author of "Queen Bees and Wannabees," a much-heralded book about girls that was written about 10 years ago.
I have found this book to be very eye-opening - I would highly recommend that you read it. It gives a lot of insight into the world that your boy is heading in to. Two of my sons (ages 15 and 9) have very volatile personalities and for the most part, with the help of books and counselors, I've learned how to see and hear past the explosive show of emotion and see the boy who is hiding underneath.
I applaud you for not ignoring this - with volatile, emotional boys it's especially important to get a handle on this while they're still little, before they're 6 inches taller than you and stronger and faster too. They need to know that you're not afraid of their emotions and can help them through the worst of how they feel.
Best of luck to you, it will get better if you work with someone who can help you help your child.
PS - the author of "Masterminds and Wingmen" actually makes a pretty good case for why video games, even moderately violent ones, aren't a bad thing. There are several keys to responsible, healthy gaming though, such as no gaming during the school week (we take the controllers on Sunday night and give them back on Friday afternoon), limited gaming time on weekend days, and allowing more gaming if it's social in nature (e.g. a friend comes over and they're both on the couch playing together).
If you don't have a TV and make the move to limit gaming to weekends only, you may have to compromise and find some other way for him to relax and zone out during the week, when his homework and chores are done. Maybe allow him to watch some shows via Netflix streaming or Hulu or something...I honestly think that some TV is better than playing video games every day, but that's of course a level of detail that you can get to with a counselor and tailor a plan that's best for your family.